This relates generally to touch sensors and, more particularly, to reducing noise in touch sensors.
Electronic devices such as tablet computers and cellular telephones often include capacitive touch sensors. A capacitive touch sensor has an array of electrodes that can be used to measure the position of a user's finger or an external device such as a touch sensor stylus. In an active stylus design, circuitry in a stylus emits signals that are detected by the touch sensor electrodes. The use of active stylus designs can help improve stylus performance.
There are challenges associated with using capacitive touch sensors to gather stylus input. Touch sensors are often mounted over displays to form touch sensitive displays. Displays have signal lines such as data lines that can emit noise. The noise can interfere with the operation of the touch sensor and can make it difficult to obtain accurate position information for a stylus. Unless care is taken, stylus data may be inaccurate or may require overly complex signal processing operations.
It would therefore be desirable to be able to provide an improved touch sensor system for an electronic device.